Retaining means for electrical plug and receptacle assemblies



Feb. 12, 1957 MALY 2,781,498

C. M. RETAINING MEANS FOR ELECTRICAL PLUG AND RECEPTACLE ASSEMBLIESFiled Nov. 19, 1953 3 Sheets-Sheet l INVENTOR (741/0? M/Valq 5/3ATTORNEY Feb. 12, 1957 2,781,498

C. M. MALY RETAINING NS FOR CTRICAL PLUG AND R PTACLE EMBLIES Filed Nov.19, 1953 3 Sheets-Sheet 2 INVENTOR /I/J ATTORNEY Feb. 12, 1957 c. MQMALY2,7

RETAINING MEANS FOR ELECTRICAL PLUG AND RECEPTACLE ASSEMBLIES Filed Nov.19, 1955 3 Sheets-Sheet 3 8 ha ATTORNEY United States Patent RETAININGMEANS FOR ELECTRICAL PLUG AND RECEPTACLE ASSEMBLIES Claude M. Maly, NewYork, N. Y.

Application November 19, 1953, Serial No. 393,152

9 Claims. (Cl. 339-91) This invention relates to retaining means forelectrical plug and outlet or receptacle assemblies, cord connectors,taps, sockets, back-connectors, interchassis connectors, plug-in unitsand similar devices.

The principal object of the invention is to provide a plug andreceptacle assembly which combines the advantages of industrialheavy-duty and standard convenience type assemblies of this character,and wherein the current conducting male and female contact members arerelieved from any and all mechanical stresses, such stresses beingassumed and carried by the novel retaining means.

A further object of the invention is to provide retaining means whichrender a plug and receptacle assembly positively shakeproof, preventaccidental disconnection, do not carry current, and which may beactuated by one hand without disengaging the male from the femalecontacts.

A still further object of the invention is to provide a plug andreceptacle assembly in which the dimensions of the contacts do notdiffer from those of prior devices, and whose novel plug may be used inconnection with standard receptacles and vice versa.

A yet further and more specific object of the invention is to provide anovel plug and receptacle assembly which will carry comparatively highcurrents with standard blades while supporting a substantial length ofheavy connecting wire, which will resist a certain pull, and which willmaintain the male and female members in conductive contact even aftertheir initial resiliency has been lost.

The invention resides essentially in the provision of a plug-receptacleassembly having any desired contact arrangement and embodying the novelretaining means consisting of male fastening members attached to aplatform which is axially slidable along the periphery of the plug, andof female fasteners contained in the receptacle. As the female fastenersare stationary while the male members are uniformly slidable in theaxial direction of the plug, their engagement or disconnection isentirely independent from the function of the contacts. Each malefastener has an elongated rounded, slotted or rectangular body which isengaged through friction by a corresponding female member, or a singlefemale fastener may be provided for retention of the male fasteners.Both the male and female members are so constructed that theirseparation requires a force greater than their connection, theconnection being at all times of a non-locking nature.

Various additional objects, features and advantages of the novelassembly will become apparent in the course of the following detaileddescription of the embodiments illustrated in the accompanying drawing,and the invention will be finally pointed out in the appendedclaims.

In the drawing,

Fig. 1 is a perspective view of a preferred embodiment of the improvedplug with two male fastening members;

Fig. 2 is a front view, partly in vertical section taken on line 2--2 inFig. 3;

Fig. 3 is a top view of the plug shown in Fig. 1;

Patented Feb. 12, 1957 Fig. 4 is a side elevational view, partly invertical section taken on line 4-4 in Fig. 3;

Fig. 5 is a horizontal section taken on line 5-5 in Fig. 2;

Fig. 6 is a plan view of the improved receptacle for the plug of Fig. l,partly in horizontal section taken on line 6-6 in Fig. 7;

Fig. 7 is an end view of the receptacle, partly in vertical sectiontaken on line 7-7 in Fig. 6;

Fig. 8 is a vertical section of a modified male fastening member;

Fig. 9 is a vertical section of a female fastening member for the malemember shown in Fig. 8;

Fig. 10 is a plan view of the female member of Fig. 9;

Fig. 11 is a side elevational view, partly in section, of anotherembodiment of a male fastener;

Fig. 12 is a vertical section of the female member for the fastenershown in Fig. 11;

Fig. 13 is a plan view of the female member shown in Fig. 12;

Figs. 14 and 15 are front and side views, respectively, of another formof a male fastener;

Fig. 16 is a side view, partly in section, of the plug engaging amodified receptacle with male fasteners shown in Figs. 14 and 15;

Fig. 17 is a horizontal section taken on line 17-17 in Fig. 16; and

Fig. 18 is a vertical section Fig. 17.

Referring now in more detail to the drawing, and first to Fig. 1, theplug 20 is a single piece of plastic material, such as Bakelite(trademark), molded to shape, having a platform member 21 to which themale fasteners 22 are secured. Platform member 21 has an inner opening23 of substantially the same configuration as the exterior contour ofthe upper handgripping portion 24 of the plug. This contour includesfour opposed circular portions 25, two opposed circular indents 26, andtwo opposed rectangular vertical grooves 31 which extend through thelower part 20a of the plug. An opening 27 for the passage of electricalconductors 28 (shown in dot-dash lines) is provided in the handgrippingportion 24. Two keys 30 support the platform member 21 in position withrespect to the plug 20 by fitting in the respective grooves 31. Thelower part 20:: of the plug 20 has a detachable plate 32 held by screws33 (see Figs. 2 and 4).

The fastening members 22 each have their upper ends provided with ashoulder 34. Their tops are upset, i. e., riveted as at 35. Slot 3511has the cross-section of cutout 36 but is somewhat closed through theriveting 35. The cutout 36 extends through most, though not all, of thelength of the male fastening member 22.

The cross-sectional shape of a male fastener 22 is shown in Fig. 5. Itis circular save for the cutout 36 forming forks 37 to engage asubstantially rounded interior wall 38 which serves as a stop dog forthe member 22. Interior wall 38 prevents the male fastener from beingextracted from the plug 20 after assembly.

Male contact members 40 are secured to the plug 20 and suitablyconnected to the electrical conductors 28 in a manner well known tothose skilled in the art, not shown.

Curved cutouts 41 provide room for two fingers or finger tips to pullthe platform member 21 upwards in order to disengage the male fastenersfrom the receptacle 50, shown in Figs. 6 and 7. Such disengagement couldbe performed by, for example, pushing with the thumb against the top 24aof handgripping portion 24 of the plug 20 while the bent index andmiddle fingers, inserted into the curved cutouts 41, pull the platform21 in the opposite direction, he, toward the top surface 24a.

A receptacle for the plug 20 has the general contour taken on line 18-18in as shown in Fig. 6, and in its preferred embodiment two diametricallyopposed sockets 51 with cutouts 67 (Fig. 7). A bottom plate 52, securedto the peripheral wall of the receptacle by screws 53 prevents socketmembers 56 from falling out of their holes. Receptacle St has arectangular opening 55 for each of the male contact members 40, shown indot-dash lines. Slotted resilient socket members 56 within socket walls57 are provided with flanges 66 received in cutouts 67. The outerdiameter of each socket member 56 is somewhat smaller than the diameterof socket 51, and the inner diameter of each socket member 56 isslightly smaller than the diameter of a male .fastener 22. Differentembodiments of male and female fastening members are shown in Figs. 8 to1 5.

grooves 63 and beads 64 are so shaped as to render inser-,

tion of a male fastener 60 into the socket member possible with but asmall effort, while the extraction of member 60 requires a substantialeffort. The upper, or lower, or both edges of grooves 63 and beads 64are thus slightly rounded and flattened which, however, is not readilyrecognizable from the drawing. The resiliency of each female fastener 65is due to the slot 62a.

Another embodiment of the male fastener is shown in Fig. 11, wherein afastening member has a rectangular contour (see Fig. 13) andlongitudinally spaced indents 71, each defined by a pair of inclinedwalls. The corresponding socket 72 (see Fig. 12) houses a U-shapedspring 73 with inwardly extending projections 74 to enter the indents 71and thus hold the male fastener in the receptacle 50. Cutout 78 infastener 70 is similar in its shape and purpose to the cutout 36 shownin Fig. 5. Cutouts 36, 62, 78 in the respective male fasteners 22, 60,70 may be omitted, as well as the interior wall 38 in the plug portion200, in which case the male fasteners may be pulled out of plug 20completely.

The free ends 75 of each spring 73 are suitably bent to engage theshoulders 76 of the socket.

The indents 71 on fastening member 79 and the angular projections 74 onspring 73 are so shaped as to make insertion of male fastener 79 intothe socket 72 possible with but a small effort while rendering theextraction of fastener 70 from the socket 72 more difficult. For thispurpose, the edges of each indent 71 and each projection 74 are slightlyrounded and flattened which, however, is not readily recognizable in thedrawing. The socket 72 has a rectangular entrance hole 77.

Figs. 16 and 17 illustrate another embodiment of the invention whereinthe plug 20 is inserted into a receptacle 80 containing a femaleretaining member 96. The platform 21 of plug 20 carries a pair ofsimilar male fasteners 81, 82, shown in Figs. 14- and 15. The upper endsof fastening members 81 and 82 are upset in rivet fashion, as at 83. Theelongated retaining leg 84 has its lowermost endbent over to form a nose90 consisting of portions 85 and 86, the latter having a pair ofinclined surfaces 87, 88 and a pointed edge 99a therebetween. A slot 89is provided bctweenthe portion 86 and the leg 84 of the male fastener topermit slight movement 'of the nose with respect to the leg 84. Thesurfaces 87 and 88 on nose portions 90 are so inclined as to makeinsertion of male fasteners 31 and 82 into openings past spring 96possible with but a small effort while rendering their extraction moredifficult; however, this is not readily recognizable in the drawing.

The receptacle $0, shown in Figs. l6, l7 and18, of a suitable insulatingmaterial, such as Bakelite (trademark), consists of a cup-shaped member91 closed by a round plate 99 ofinsulating material which is securedthereto by a number of screws 93. The end .wall of cup-shaped member 91opposite the plate 99 has an opening 94 for the electrical conductors,not shown. Plate 99 has a flat outer surface, a cylindrical portion 101?extending into the cup-shaped member 91, and a peripheral flange 98 atthe free end of the cylinder 100. Cylinder has a pair of inwardlyextending projections 79. Rectangular openings 95 in the plate 99 passthrough the projections 79 and adjacent portions of cylinder 1G0 andflange 98 to receive the legs 84 and nose portions 99 of the malefastening members 81, 82 (see Fig. 16).

The upper side of flange 98, the periphery of the cylinder 100 and theinner side of plate 99 form a groove 192 (see Fig. 18) which seats acircumferentially disposed helical spring 96 whose ends are interlockedas at 97 (see Fig. 17). When the legs 84 of the male fasteners 81, 82are inserted into the holes 95, the inclined walls 88 of their noseportions 99 force the expansion spring 96 radially outwardly away fromthe periphery of cylinder 1% between theinner surface of plate 99 andthe.

upper surface of flange 98 until the peaks 90a pass the innermost partof spring 96, whereupon the spring contracts radially inwardly over theinclined surfaces 87 of the nose portions 9%) to retain the fasteners81, 82 in the receptacle 89. When the legs 84 of the male members 81, 82are extracted from the receptacle, the inclined surfaces 87 of theirnose portions 90 cause the spring to expand, and after the peaks 90apass its innermost portion, the spring 96 again contracts by slidingalong the surfaces 88 to find its normal position between the innersurface of plate 99, periphery of cylinder 100 and the upper surface offlange 98, ready for the next entry of the male fastening members.

The plate 99 is provided with openings 101 which are somewhat largerthan the cross-section of a contact member 40 (see Fig. 17).

In this embodiment, the lower part 20a of the plug 26 has a cutout'1tl3adjacent each opening 95 to accommodate nose portions 90 of members 81,82 when the platform member 21 with the male fasteners is slid away fromthe receptacle 80.

Common to all embodiments of my invention is the principle of providingmale and female fastening members which insure a firm but not lockingconnection between the plug and receptacle in order to reserve theaction of the'contact members entirely for the conduction of current.'Ihc fastening members relieve the contact members of any and allmechanical stresses. The novel assembly may be used in householdappliances, small or medium sized electrical, industrial or farmapparatus, or plug connected electrical devices in general, as well asin cable connectors, cube taps, cube adapters and the like.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described for obviousmodifications will occur to persons skilled in the art within the spiritand scope of my invention as defined in the appended claims.

1 claim:

1. In a separable plug and receptacle assembly, the combination of aplug of insulating material having a first and a second extremity, malecontacts extending from said first extremity and a reduced handgrippingportion adjacent said second extremity of said plug, a platform memberwith an opening for slidably receiving said handgripping portion of saidplug and elongated fasteners parallel with and spaced from said malecontacts and each having a first and a second end with said first endattached to said'platforrn member, said plug having a plurality of boresbetween said reduced handgripping portion and said first extremitythereof for slidably receiving said fasteners; whereby said second endsof said fasteners may be withdrawn into said plug between said firstextremity and saidreduced handgripping portion thereof when saidplatform member is slid along said reduced handgripping portion towardsaid second extremity of said plug, with a receptacle of insulatingmaterial having female contacts for reception of said male contacts, aplurality of sockets for said second ends of said fasteners when saidmale contacts are inserted into said female contacts and said platformmember is slid along said handgripping portion toward said firstextremity of said plug, and retaining means in said receptacle spacedfrom said female contacts for releasably engaging said second ends ofsaid fasteners.

2. The combination of claim 1, wherein said plug has a plurality ofparallel grooves extending between said extremities thereof, and saidplatform member has a plurality of projections extending into saidgrooves, the distance between said extremities of said plug exceedingthe length of said fasteners.

3. The combination of claim 1, wherein each of said fasteners has anelongated cutout terminating in the proximity of said second endsthereof, and stop means is provided for retaining said fasteners in saidplug including a plurality of keys extending into the respective cutoutsin said fasteners, and said retaining means in said receptacie includesa resilient slotted tubular member in each of said sockets anchored insaid receptacle for frictionally engaging and retaining a fastenerinserted therein.

4. The combination of claim 3, wherein said fasteners have a pluralityof longitudinally spaced circumferential grooves in the proximity ofsaid second ends thereof and said tubular members have a plurality oflongitudinally spaced internal beads received in said grooves when said'a." eners are inserted into said tubular members.

5. The combination of claim 1, wherein said fasteners each have arectangular contour and a plurality of spaced angular indentstransversely of the greatest dimension thereof, and said retaining meansinclude a resilient member of U-shape inserted into each of saidsockets, said resilient members each having a plurality of inwardlyfacing projections transversely of the greatest dimension thereofreceived in said indents when said fasteners are inserted into saidsockets in said receptacle.

6. The combination of claim 1, wherein each of said fasteners includes anose portion at said second end thereof, said nose portions having anedge transversely of the greatest dimension of said fasteners defined bya pair of inclined surfaces, and said retaining means is a helicalspring circumferentially adjacent said sockets in said receptacle forengaging one of said inclined surfaces when said fasteners are insertedinto said sockets, said bores for said fasteners in said plugterminating in enlarged cutouts at said first extremity of said plug forreception of said nose portions when said platform member with saidfasteners is slid along said reduced handgripping portion toward saidsecond extremity of said plug.

7. The combination of claim 6, wherein said receptacle includes a cupshaped body and a plate attached to the open end of said body, asubstantially cylindrical portion extending from said plate into saidbody and an annular flange at the free end of said cylindrical portion,said spring being inserted between said plate and said flange adjacentthe periphery of said cylindrical portion, with said sockets extendingthrough said plate, said cylindrical portion and said flange.

8. In a separable plug and receptacle assembly, the combination of aplug of insulating material having a first and a second extremity, malecontacts extending from said first extremity, a reduced handgrippingportion adjacent said second extremity and an enlarged portion betweensaid handgripping portion and said first extremity of said plug with acircumferential shoulder between said enlarged and said handgrippingportion, a platform member having an opening for slidably receiving saidhandgripping portion between said shoulder and said second extremity ofsaid plug, a pair of elongated rodlike fasteners parallel with said malecontacts and each having a first and a second end, the distance betweensaid extremities of said plug exceeding the length of said fasteners,said first ends of said fasteners being attached to said platform memberadjacent two opposing sides of said handgripping portion of said plug,said enlarged portion of said plug having a pair of parallel boresbetween said shoulder and said first extremity thereof with saidfasteners inserted into said bores and projecting with said second endsfrom said first extremity of said plug when said platform member isadjacent said shoulder, each of said fasteners having an elongatedcutout terminating in the proximity of said second end thereof and saidenlarged portion of said plug having a pair of keys extending into therespective ones of said bores therein and into said cutouts in saidfasteners, with a receptacle having a cupped body portion, a plateattached to and closing the open end of said body portion, femalecontacts in said receptacle for reception of said male contacts whensaid enlarged portion of said plug is adjacent said plate, a pair ofsockets in said plate for entry of said fasteners and an enlargedslotted tubular retaining member of resilient material in each of saidsockets for receiving and frictionally engaging said second ends of saidfasteners inserted into said sockets.

9. The combination of a plug of insulating material having a first and asecond extremity, male contacts extending from said first extremity, areduced handgripping portion adjacent said second extremity, a bodyportion between said reduced handgripping portion and said firstextremity, and a shoulder between said body portion and saidhandgripping portion, with a platform member having an opening forslidably receiving said handgripping portion, and a plurality ofelongated fasteners parallel with said male contacts and each having afirst and a second end, said first ends of said fasteners being attachedto said platform member, said body portion of said plug having aplurality of bores, one for each of said fasteners for slidablyreceiving said fasteners, said second. ends of said fasteners projectingfrom said first extremity of said plug when said platform member isadjacent said shoulder, the distance between said extremities of saidplug exceeding the length of said fasteners, whereby said second ends ofsaid fasteners may be withdrawn into said body portion when saidplatform member is slid away from said shoulder along said handgrippingportion toward said second extremity of said plug.

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